What is the transform field in the occurrence field when I query the assembly API doing?

What is the transform field in the occurrence field when I query the assembly API doing? The transformation matrix is exerted on which matrix I can query from?Are there anyways that I can see the location of the mate connector in the coordinate system that can tell me in what ways are the parts or subassemblies are transformed or reoriented in the current coordinate system and formed this current assembly?